Global warming Key words: combustion, carbon dioxide, methane, deforestation

Rising levels of carbon dioxide. Why? starter Rising levels of carbon dioxide. Why? At the moment the change is seemingly very small at 0.060C per year

How does combustion affect the atmosphere? Objective How does combustion affect the atmosphere? Success Criteria By the end of the lesson I: know how combustion affects the atmosphere know how living organisms affect the can explain the consequences of global warming

Get the gas right Pollution problem Gas Global warming Carbon dioxide Acid rain Sulfur dioxide and nitrogen oxides Holes in the ozone layer CFCs (Chloroflurocarbons)

The greenhouse effect

Draw a diagram and explain the ‘greenhouse effect’ Teacher notes This four-stage animation can be used to illustrate the principles of the greenhouse effect. Students could be asked to consider the impact of rising greenhouse gases on the natural phenomenon of the greenhouse effect.

Atmospheric carbon dioxide The worry of rising carbon dioxide levels is that if the earth warms up then the ice caps will melt causing sea levels to rise. There is no evidence of this happening but it would mean that low lying areas will flood and parts of or even whole countries will become submerged! Teacher notes This graph was produced using data sourced from the Mauna Loa Observatory, Hawaii, courtesy of NOAA (the National Oceanic and Atmospheric Administration). More information about atmospheric gases is available at www.cmdl.noaa.gov.

Carbon dioxide levels Carbon dioxide is one of the most important greenhouse gases because atmospheric concentrations have risen dramatically over the past century. Why do you think this is? Respiration and combustion produce carbon dioxide Photosynthesis removes carbon dioxide More rice fields and cattle have led to increased levels of methane in the atmosphere. Increased levels of greenhouse gases (carbon dioxide and methane) may cause global warming as a result of the Greenhouse effect Burning fossil fuels (combustion), deforestation and flooding land for the construction of hydroelectric dams have all contributed to rising levels of carbon dioxide. Another greenhouse effect harming the environment is methane which is produced by cows in large amounts and by rice fields!

Global warming and greenhouse gases One of the greatest threats caused by air pollution is global warming. Global warming is caused by a build-up of greenhouses gases, which leads to an increase in the Earth’s temperature. A greenhouse gas is an atmospheric gas that absorbs infrared light. Key greenhouses gases include: carbon dioxide (CO2) Teacher notes See the ‘Climate Change’ chemistry presentation for more information on greenhouse gases, the greenhouse effect and global warming. methane (CH4) water vapour (H2O) nitrous oxide (N2O)

Global warming Most fuels contain carbon Carbon dioxide is released when fuels like gas, coal, oil, petrol and wood are burned. Greenhouse gases cause the temperature of the Earth to rise slowly. This causes climate change. Methane released from cattle and rice fields is also a greenhouse gas. Carbon dioxide released when fuel burned Extra carbon dioxide in the air slows down heat loss from Earth Climate change

What is the carbon sink? Before the industrial revolution, carbon dioxide levels were usually kept in check by the carbon sink – forests and oceans that capture and store carbon. forests – All green plants absorb carbon dioxide as part of photosynthesis. The absorbed carbon is only released back into the atmosphere when the plant dies and rots, or is burned. oceans – Carbon dioxide dissolves in sea water, depending on the temperature and pressure. Tiny marine animals called phytoplankton extract carbon from the carbon dioxide to make their skeletons and shells.

The carbon sink

Deforestation Deforestation can have a contributing effect on global warming. Large scale deforestation (especially in tropical areas) has led to an increase of carbon dioxide in the atmosphere (when trees die they release their CO2) It has also reduced the amount of CO2 that is removed from the atmosphere Leads to loss of biodiversity. some organisms lost may have been needed in the future!

Preventing global warming Energy efficiency means less fuel burned to make electricity. Fuel cell buses. Renewable energy sources like water power, solar, wind farms, bio fuels. Nuclear power. The Kyoto agreement to reduce CO2 emissions. Reduction in large scale deforestation

Exam Questions Give one reason why deforestation increases the carbon dioxide concentration of the atmosphere. (1 mark) Explain, as fully as you can, why the increasing concentration of carbon dioxide in the atmosphere is causing global warming.

How does combustion affect the atmosphere? Objective How does combustion affect the atmosphere? Success Criteria By the end of the lesson I: know how combustion affects the atmosphere know how living organisms affect the can explain the consequences of global warming